FBI(WASHINGTON) -- Details in a police report made public Tuesday suggest that Navy Yard shooter Aaron Alexis may have been losing touch with reality just weeks before he went on a shooting rampage in Washington, D.C.

Alexis called police in Newport, R.I., on Aug. 7 after he switched hotels three times because he heard voices in the walls and ceilings talking to him, trying to keep him awake, and he wanted to file a harassment report, according to police documents.

Alexis told police that he heard voices that he feared were "sending vibrations through his body" and were out to harm him, noting that he had gotten into an argument on a plane to Rhode Island and he was convinced the person he argued with had sent three people to follow him.

Alexis "stated that the individuals are using 'some sort of microwave machine' to send vibrations through the ceiling, penetrating his body so he cannot fall asleep," officers wrote in the police report.

Police questioned Alexis about whether he had any prior mental issues or episodes and any family history of mental illness, but Alexis said he did not. They then notified the Navy police and faxed a copy of the report to the Navy about Alexis's complaints.

The episode showed a disturbed Alexis battling mental issues just weeks before he went to the Navy Yard in Washington, D.C., and opened fire on workers there, killing 12 individuals Monday morning.

Alexis, 34, was killed when police rushed to the scene and exchanged gunfire with him.

He had long complained that he suffered from post-traumatic stress disorder from helping to clean up after the 9/11 attack of the World Trade Center, but New York officials said they have no record of Alexis working at Ground Zero.

What is clear is that Alexis, a former Navy reservist, struggled with anger issues, outbursts and violence long before he walked into the Navy Yard complex.

Prior to his August call to cops in Rhode Island, Alexis had multiple run-ins with law enforcement agencies around the country as well as the Navy, which negotiated an honorable discharge with Alexis after failing to get a general discharge.

In 2004, Alexis told police that he flew into an "anger-fueled blackout" and shot out the tires of another man's vehicle because the man had allegedly been watching him, according to Seattle police, who arrested Alexis at the time.

Alexis told cops that he could not remember firing his gun at the man's car until an hour after the incident, according to a police report released Monday. A Seattle detective then spoke to Alexis's father, who was "curious" about the incident.

"Mr. Alexis then told me that his son had experienced anger management problems that the family believed was associated with PTSD," the detective wrote in a police report. "He confirmed that his son was an active participant in rescue attempts of September 11th, 2001."

But officials in New York said there is no record of Alexis working as an official responder or cleanup worker.

"He was not on any official list," one official told ABC News.

Alexis could have been a volunteer who went to Ground Zero on his own to help out, but that information would not be able to be confirmed unless a witness came forward to say they saw him there, the official said.

Whether Alexis's problems actually stemmed from 9/11, his behavioral issues were apparent for years before the shooting.

"I know Aaron had some post-traumatic [stress disorder] from being in the military," his friend Melinda Downs told ABC News. "He went to the VA and they would give him some medicine."

In addition to Alexis's claim of PTSD, he struggled to connect with his family and win his father's approval, Downs said.

"I know he lived in New York. He moved here from Boston," Downs said. "I know that he said that he has some issues with his family [but] he was never like, 'I hate this person, I hate that person.'"

"Aaron felt not manly enough for daddy's approval. So that's what he said," Downs recalled. "Aaron would say, 'People think I'm not a man because I'm soft-spoken or to myself or quiet when I speak.' He felt a little let down."

Alexis was also a Buddhist who believed in meditation to relieve stress, she said. He would practice meditation and also encouraged his friends to do so. She said she never would have imagined him shooting innocent people.

During his stint in the Navy, Alexis exhibited a pattern of misconduct that included eight to 10 infractions, ranging from a traffic violation to unexcused absences, according to a Navy official. There was also an arrest in 2010 for firing his gun through a neighbor's floor. He claimed it was an accident and was not prosecuted, according to the district attorney's office in Tarrant County, Texas.

And one person close to Alexis said she suspects he repaid her kindness with mischief.

Kristi Suthamtewakul told ABC News that she was convinced that Alexis poured sugar into her new Honda Accord, even though she let him live in her home and work at her restaurant. Suthamtewakul said Alexis had become frustrated when she was unable to drive him to job interviews and to buy groceries.

But Suthamtewakul's husband, Nutpisit, said there was no way Alexis was capable of shooting innocent people.

"He's not aggressive," Nutpisit Suthamtewakul, a friend and former roommate of Alexis's, told ABC News. "He had a gun, but that doesn't mean he's going to shoot people. He had a concealed-weapons permit."

Nutpisit Suthamtewakul said Alexis liked to play games, drink and party. Alexis spoke Thai fluently, he said, traveled a lot for work and had been living in Washington for four or five months.

"I don't believe he did that," Suthamtewakul said. "He can be tough physically, but I don't think he'd kill people."